International patent application WO 2009/142488 discloses a semiconductor processing apparatus capable of processing semiconductor substrates in continuous succession. The apparatus features a process tunnel defining a linear track along which substrates may be transported while being processed. During transport and processing, the substrates may be floatingly accommodated between two gas bearings, which gas bearing may both enable contactless substrate propulsion and provide for a reactive or non-reactive processing environment. Compared to the batch wise processing encountered in conventional vertical and horizontal (thermal) furnaces, the apparatus of WO'488 offers significantly improved throughput rates on the order of thousands of substrates per hour.
The process tunnel of the apparatus may be relatively long, e.g. on the order of several meters, and define a practically closed process tunnel space that is not accessible for maintenance or repair without shutting down the (production of the) apparatus as a whole. With possibly thousands of fragile semiconductor substrates whizzing through the tunnel space per hour, a tool to monitor the behavior of both individual substrates and sets of substrates, to detect abnormalities in the processing thereof, and to enable swift corrective action is practically indispensable.
It is an object of the present invention to provide for such a monitoring and control tool.